Conventionally, antennas having a configuration in which two sheets of conductive plates having conductivity are disposed at a predetermined distance from each other, and slots are formed in one of the conductive plates have been known. With this configuration, radio waves propagated between the two sheets of conductive plates are radiated outside from the slots. Patent Document 1 discloses an antenna similar to such kind of antennas.
Patent Document 1 discloses a microstrip antenna having a configuration formed with a plurality of probes formed to pass through the center of the conductive plates. In Patent Document 1, an effect that a radiating direction of a beam can be substantially matched with normal directions of the conductive plates, an effect that a frequency property of the antenna improves, and the like by forming the probes as above, are disclosed.
Patent Document 2 discloses a slot array antenna where slots are arrayed in one direction. In Patent Document 2, a probe is disposed inside a coaxial waveguide converter. By disposing the probe as above, a mode of an electromagnetic wave to be transmitted can be switched.